This invention relates to a high pressure fuel injection unit for an engine, and more particularly to an improved feeder wire structure for energizing an electromagnetic assembly of the injection unit.
One popular form of fuel injection unit for engines is the so-called "accumulator type." This type of injection nozzle includes an accumulator chamber that is charged with fuel under pressure and which communicates with a nozzle port. An injection valve is supported within the accumulator chamber and controls the discharge through the nozzle port. An actuating device is associated with the injection valve and is moveable within a control chamber that is also pressurized with fuel. A valve is associated with the control chamber and is opened so as to reduce the pressure and cause the pressure in the accumulator chamber to unseat the injection valve and initiate fuel injection. Typically, the valve is operated by a main electromagnetic assembly that is contained within the housing of the fuel injection nozzle.
To control the amount of fuel injected, the inventors have proposed to provide an additional and separate sub-electromagnetic assembly within the accumulator chamber to control the lift movement of the injection valve. It has also been proposed to provide a wire passage which extends radially through the side wall of the accumulator chamber in which a wire harness is supported for operating this sub-electromagnetic assembly. Although this type of feeder wire structure is generally satisfactory, the angular orientation of the wire passage in relation to the housing can give rise to sealing, size and installation problems. For example, when the wire passage extends perpendicularly or at an angle to the housing axis, the side wall of the accumulator chamber is usually not thick enough to provide a sufficient seal around the wiring passage so as to withstand the high pressure within the accumulator chamber. This typically has required that the diameter of the fuel injection unit be enlarged to improve the effectiveness of the seal. In addition, when the wire passage is disposed at an angular relationship to housing axis, the wires may interfere with the engine or other components which can make installation of the injection unit in the engine difficult.
It is, therefore, a principal object of this invention to provide an improved feeder wire structure for an electromagnetic assembly within the accumulator chamber of this type of fuel injection unit.
It is a further object of this invention to provide an improved feeder wire and sealing structure for this type of fuel injection unit which is capable of withstanding the high pressure in the accumulator chamber.
It is yet another object of this invention to provide an improved feeder wire and sealing structure for an accumulator type fuel injection unit which provides a sufficient seal without the need for increasing the outer diameter of the injection unit.
It is still another object of this invention to provide an improved feeder wire structure which does not present a problem with respect to installation of the injection unit in the engine.